Too bad that one builds a cheap battery that is not to change

I had purchased the toothbrush to my wife's birthday and we use it only once a day, since we also use ordinary manual toothbrushes, and only in the evening electrically clean the teeth.
However, it is a shame that so quickly, the battery gives up the ghost, and not to replace itself.
Such costs, even if it is of high quality at most a few euros.
We have practically invite brush after two times the machine every day, because it does not last longer than 5 minutes.
This is a definite no-go.
Cleaning, however, is top and the 2 minute display I find also very convenient.